In U.S. Pat. No. 3,706,383, I have disclosed and claimed a fluid separator with a rotatable spiral conduit inside a housing. The spiral conduit has interior transverse abutments positioned in the path of fluid flow through the conduit and openings near these abutments for the escape of heavier constituents of the fluid stream flowing through the rotating spiral conduit.
In my co-pending U.S. patent application, Ser. No. 312,041, filed Dec. 4, 1972, and entitled "Separator", now U.S. Pat. 3,768,658, I have disclosed and claimed a modified arrangement having an internal cylindrical wall which extends between and joins successive turns of the rotatable spiral conduit so that three fluid passageways are provided: the interior of the spiral conduit itself; the space inside the internal cylindrical wall (at the inside of the spiral turns of the conduit); and the annular space between this internal wall and the outer housing (at the outside of the spiral turns of the conduit). The spiral conduit has interior abutments and nearby openings at the outside or the inside, or both, of its turns to enable the separation of fluid constituents introduced into the spiral conduit, and/or into the annular space outside its turns, and/or into the generally cylindrical space inside its turns.